The present invention provides a process of performing a swing bed regeneration operation that prevents downstream or recycle units from experiencing large fluctuations in flowrate or contamination with regeneration fluid. A swing bed regeneration operation involves at least one treating vessel that is operating on-line and at least one additional treating vessel that is off-line for regeneration. When the treating vessel operating on-line becomes spent, the regenerated vessel is brought on-line while the spent vessel is taken off-line. The spent vessel, now off-line, is regenerated, and the operation continues.
Traditionally, after regeneration of the off-line vessel is complete, a portion of the effluent from the vessel on-line is used to displace regeneration fluid from the off-line regenerated vessel. The regeneration fluid may be a rinse solution, wash solution, or the regenerant itself, whichever was last introduced to the vessel. The displacement step is necessary so that when the regenerated vessel is brought back on-line, the immediate effluent does not contain regeneration fluid, for if regeneration fluid were present in the effluent, it may harm or upset downstream or recycle units. However, in diverting a portion of the effluent from the on-line vessel to displace regeneration fluid from the off-line vessel, the flowrate of effluent to downstream or recycle units is decreased for the duration of the displacement. As much as ten to twenty percent of the effluent from the on-line vessel is typically diverted to perform the displacement resulting in a ten to twenty percent decrease in flowrate to downstream or recycle units. In some processes, the regeneration must be performed daily thereby causing the flowrate to drastically change every day. The downstream or recycle units may suffer significant upsets as a result of the periodic fluctuation of the flowrate.
To prevent the flowrate of effluent to downstream or recycle units from fluctuating while also preventing regeneration fluid from contaminating the effluent from the regeneration operation, the present invention requires a displacement surge drum to be installed between the effluent output of the vessel on-line and the fluid input of the vessel off-line. The flowrate of effluent from the displacement surge drum is controlled so that the overall flowrate from the regeneration operation remains stable. The composition of the effluent conducted to downstream units also remains stable since any regeneration fluid present in a regenerated vessel is displaced with process fluid prior to the vessel being brought on-line. This invention is especially useful when the solid treating particles require frequent regeneration that would otherwise result in frequent process upsets.